Use a UV light. The blood stain will appear black.
A PVC cleaner will remove oil deck stain from the vinyl part of a window. Pour the cleaner on a clean sponge or rag and wipe in the direction of the grain to remove the stain.
If it's been treated with sealant odds are that it won't take stain properly. To get a good result try sanding the sealant off first.
There are reports from people stating that the use of WD-40 can help to remove the hardened wood stain from metal cranks on a window. It is best to never use anything that could rust or cause damage.
To stain rawhide, first clean and wet the rawhide, then apply leather dye or oil-based stain using a sponge or cloth. Allow the rawhide to dry completely before applying a sealant or finish to protect the stain and the rawhide.
To restain a Longaberger basket, first clean the basket with a damp cloth to remove any dirt or debris. Then, apply a wood stain or sealant using a brush or cloth, making sure to follow the manufacturer's instructions. Allow the stain to dry completely before using or displaying the basket.
The Great East Window at York Minster, York, England.
You can try using a mixture of warm water and mild dish soap to scrub the stain. If that doesn't work, you can use a paste made from baking soda and water. Apply the paste to the stain, let it sit for a few minutes, then scrub with a soft brush.
You are probably not going to remove the "stain" from the cover. It has been bleached of all pigment.
There really isn't a way to remove a paint thinner stain from wood furniture. You must repaint or re-stain the furniture.
To remove a Pentel pen stain from clothes, you can try rubbing alcohol or a stain remover directly on the affected area. Gently blot the stain with a clean cloth until it starts to lift, then wash the garment as usual. It may take a few tries to completely remove the stain.
You re-stain with a darker stain. Good luck.